PROJECT SUMMARY The overall goal of this project is to develop a motion-immune angiographic imaging technique for quantifying blood flow in a 3D vascular volume during body interventions. Time-resolved digital subtraction angiography (4D- DSA) was initially used to evaluate cerebrovascular anatomy, but has recently been extended to permit the calculation of quantitative velocity and flow information from the same dataset. Use of 4D-DSA for body interventions has been severely limited by motion-related artifact and image degradation. Motion-corrected 4D- DSA promises to be an invaluable technique for body interventions by enabling simultaneous depiction of anatomy and quantitative flow analysis within a vascular volume. The technique may improve both the safety and effectiveness for a number of procedures, including transarterial chemoembolization (TACE), a minimally invasive treatment option for patients with hepatocellular carcinoma and liver metastases. During TACE, angiographic monitoring of residual tumoral blood flow is critical and the degree of stasis achieved directly impacts patient outcomes, including survival. While efforts have been made to standardize the angiographic endpoint for TACE, it remains largely subjective and not reproducible. Therefore, there is a need for an objective, quantitative means of determining when the optimal degree of stasis has been achieved during a TACE. This proposal first focuses on the development of imaging protocols that compensate for patient and respiratory motion during 4D-DSA acquisitions. A series of animal experiments will then be performed to validate the motion correction strategies and confirm accurate blood flow and velocity calculations. Motion-corrected 4D-DSA will then be used to quantify embolization related changes in hepatic arterial blood flow, which will be correlated with changes in flow and perfusion on MRI. Finally, a clinical study will be performed in which 3D-DSA images acquired during TACE procedures will be retrospectively reconstructed using the motion-compensating 4D-DSA algorithm and analyzed. The successful completion of this project will represent a major step forward in interventional oncology by providing an angiographic technique for endpoint determination during TACE. However, the applicability of motion-compensated 4D-DSA extends beyond liver embolization to include many other procedures that are hindered by subjective or operator dependent endpoints.